1. Field of the Invention
The present invention relates to an outboard motor.
2. Description of the Related Art
In recent years, outboard motors equipped with catalytic converters have been introduced to improve environmental performance. In outboard motors equipped with catalytic converters, measures are taken to detect overheating of an exhaust pipe in order to prevent the catalytic converter from being damaged by heat. When overheating is detected, a control is executed to forcefully stop the engine or to issue a warning through an indicator device to inform a driver. In response, the driver then performs an inspection to eliminate the overheating.
When detecting overheating in this way, if incorrect detections of overheating occur frequently, then the detections will become bothersome for a driver who must conduct an inspection every time overheating is detected. Therefore, there is a demand for preventing incorrect detections of overheating. For example, Laid-open Japanese Patent Application No. 11-101172 discloses a watercraft engine exhaust apparatus equipped with an exhaust gas temperature sensor and an exhaust pipe temperature sensor. The exhaust gas temperature sensor measures a temperature of an exhaust gas at a position downstream of a catalytic converter. The exhaust pipe temperature sensor measures a temperature of a pipe wall of the exhaust pipe at a position downstream of the catalytic converter. Incorrect detections are prevented by detecting overheating using detection signals from both the exhaust gas temperature sensor and the exhaust pipe temperature sensor.